[PATCH 5.5 047/150] staging: rtl8723bs: Fix potential security hole

[Greg Kroah-Hartman]

From: Larry Finger <Larry.Finger@xxxxxxxxxxxx>

commit ac33597c0c0d1d819dccfe001bcd0acef7107e7c upstream.

In routine rtw_hostapd_ioctl(), the user-controlled p->length is assumed
to be at least the size of struct ieee_param size, but this assumption is
never checked. This could result in out-of-bounds read/write on kernel
heap in case a p->length less than the size of struct ieee_param is
specified by the user. If p->length is allowed to be greater than the size
of the struct, then a malicious user could be wasting kernel memory.
Fixes commit 554c0a3abf216 ("0taging: Add rtl8723bs sdio wifi driver").

Reported by: Pietro Oliva <pietroliva@xxxxxxxxx>
Cc: Pietro Oliva <pietroliva@xxxxxxxxx>
Cc: Stable <stable@xxxxxxxxxxxxxxx>
Fixes 554c0a3abf216 ("0taging: Add rtl8723bs sdio wifi driver").
Signed-off-by: Larry Finger <Larry.Finger@xxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20200210180235.21691-3-Larry.Finger@xxxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/staging/rtl8723bs/os_dep/ioctl_linux.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/staging/rtl8723bs/os_dep/ioctl_linux.c
+++ b/drivers/staging/rtl8723bs/os_dep/ioctl_linux.c
@@ -4207,7 +4207,7 @@ static int rtw_hostapd_ioctl(struct net_
 
 
 	/* if (p->length < sizeof(struct ieee_param) || !p->pointer) { */
-	if (!p->pointer) {
+	if (!p->pointer || p->length != sizeof(*param)) {
 		ret = -EINVAL;
 		goto out;
 	}